According to demand for miniaturization of electronic components, a large quantity of integrated circuit chips or circuit components are required to be mounted on an electronic circuit substrate on which a semiconductor integrated circuit or the circuit components are mounted. Accordingly, demand for effective use of a wiring space or a mounting space is increasing.
Particularly, a signal which is used for information processing of an electronic circuit is a digital signal in a wireless local area network (LAN) communication, and thus an analog circuit which performs wireless communication and a digital circuit which performs information processing of a signal for communication are used together.
Accordingly, there is a problem in which electromagnetic noise that is generated by an operation clock of a central processing unit (CPU), a memory, or the like in the digital circuit, interferes with the analog circuit, and thus the signal for communication is degraded.
Accordingly, a technology is known which configures an electromagnetic band gap (EBG) structure by using an open stub that is formed in a spiral shape in an electronic circuit substrate, and thereby electromagnetic noise propagating through the electronic circuit substrate is reduced (refer to, for example, Non Patent Literature 1). That is, the electromagnetic band gap structure absorbs electrical energy of the electromagnetic noise which is generated from the digital circuit, and thereby the amount of electromagnetic noise which propagates through the electronic circuit substrate is reduced and the electromagnetic noise is prevented from interfering with the analog circuit.